Liquid crystal device with reflective microstructure for attitude control

Liquid crystal devices (LCDs) are proposedas fuel-free attitude control devices for spacecraft. The LCDs consist of multiple thin layers, including polymer-dispersed liquid crystal (PDLC) and a base film that has a microstructure with aluminum deposited onto it. When a voltage isapplied to anLCD, the crystalsinthe PDLC align with the electric field, and incident light passes through the PDLC layer and is reflected by the aluminum coating, whereas it is dispersed by randomly arranged crystals when no voltage is applied. This means that arrangements of LCDs can control both the magnitude and direction of reflection electrically, and they can achieve three-degree-of-freedom attitude control using solar radiation pressure. Because light diffracted by the layers causes optical interference, the PDLC has a polarization effect, and the microstructure shape has manufacturing errors, reflection from LCDs is a complex phenomenon and it must be understood to realize the desired performance." The first sentence all means the reason for the second sentence.